London School of Hygiene & Tropical Medicine

Scottish nurse Pauline Cafferkey, who contracted Ebola while working in Sierra Leone in December 2014, has been readmitted to an isolation unit in the Royal Free Hospital due to "an unusual late complication of her previous infection." Although the virus is present in her body, it is not thought to be contagious.

Commenting on the news, John Edmunds, Professor of Infectious Disease Modelling and Dean of Faculty of Epidemiology and Population Health, said: "The Ebola virus can occasionally persist for some months in certain tissues within survivors. The risk of transmission from these individuals appears to be very low. However, with so many survivors in West Africa now, there is a risk that further outbreaks can be triggered, which is why authorities have to remain very vigilant."